Gastric motor function such as propulsion of grounded chymous into the small bowel is difficult to assess. Several methods have been employed, in the prior art, including dye dilution which requires intubation of the stomach and duodenum, radiographic studies using barium salts, and more recently developed techniques with ultrasonic and applied potential tomography equipment (Mangnall 1989). The best prior art method of assessing gastric emptying at present is, however, the use of radionuclide-labeled meals (Fisher 1990).
Gastric Emptying. With the prior art, gastric emptying of radiolabeled solids and liquids can be evaluated simultaneously when the various phases are marked with different tracers such as 99mTc and 111In respectively. Frequently used radiolabeled solid and liquid meals include chicken liver, eggs, oatmeal, orange juice and water. After ingestion of a labeled meal, anterior and posterior gamma camera images of the stomach area are obtained in 5 to 15 minute intervals for 1.5 to 2.0 hours. After correction for decay, the counts in the gastric area are plotted as percentages of total counts at the start of imaging. Results are often presented as curves of emptying for liquids or solids against time, with the 5th and 95th percentiles of normals for comparison. A simpler technique of assessment is to derive the T1/2, which is the time taken to empty 50% of a meal from the stomach. These prior art methods are performed with the patient immobilized over a relatively short time period (e.g., 2 hours) and are far from the physiological environment associated with meals.
The present invention is a system and a method for gastric emptying and gastrointestinal output using an intragastrointestinal catheter which can be used on both stationary and ambulatory basis and represents therefor a significant advantage over prior art. As compared with today's prior art method of choice, the present invention does not use an expensive external gamma camera. In addition the present invention uses an intragastrointestinal catheter reducing the amount of radiolabeled material needed. Furthermore, the present invention enables ambulatory procedures which allows for a more physiologic environment when the meals are ingested and processed.
Prior art catheters that include sensors for isotope activity have been used to assess gastroduodenal reflux of radiolabeled bile (Stoker 1990) but not gastric emptying nor gastrointestinal output from any region of the gastrointestinal tract. Ambulatory data acquisition recorders are well known for assessing 24 hour pH and pressure from various parts of the gastrointestinal tract, but monitoring gastric emptying or output on an ambulatory basis in a physiological environment in the clinic or in the patient's home has not previously been taught.
It is an object of the present invention to provide a stationary and ambulatory system with which gastric emptying and gastrointestinal output from any part of the gastrointestinal tract can be assessed. It is a further object of the present invention that patients undergoing a gastric emptying test with radiolabeled liquids and solids shall be able to take their meals in as normal circumstances as possible. It is yet a further object of the present invention that the amount of ingested radiolabeled material can be reduced as compared with present stationary gamma counters. It is yet a further object of the present invention to enable simultaneous measurement of said radiolabeled material with other parameters such as pH, bile, EGG, IGG and pressure. It is yet a further object of the present invention to present a unique software data acquisition program for recording, analysis and reporting gastric emptying and intragastrointestinal output procedures, said program also including provisions for defining and carrying out other procedures of the gastrointestinal tract, said program also including provisions for including results of said procedures in a patient journal database system.
Other methods with which this invention can be compared include stationary gastric emptying (as opposed to gastric output) studies in which radiolabeled liquids or solid meals are administered to a patient in and which the patient is positioned under a external gamma-camera which registers the declining isotope activity from the stomach as the stomach empties its contents. Unlike the present invention such methods are performed under unphysiological conditions, offer no means for ambulatory measurement of gastric emptying or output, offer no means for placing the sensor directly in the flow stream of the material to be measured, and offer no means for measurement of other parameters on a simultaneous basis.